The present invention relates to certain novel bone implants and their use for bone repair or reconstruction.
Broadly described, the implants of the invention comprise a mixture of Plaster of Paris (PP) or equivalent forms of calcium sulfate hemihydrate, hereinafter referred to for convenience as "plaster", and calcium phosphate ceramic particles, the plaster functioning as a malleable, biodegradable "scaffold" or binder to hold the ceramic particles together.
According to one embodiment of the present invention, it is necessary for successful bone implants to use both the plaster and a relatively non-resorbable calcium containing material, such as calcium phosphate ceramic. The plaster, as noted, serves as a scaffold for the ceramic, contains the mixture in a desired physical form to fill a bony cavity or defect, and augments form or contour. The plaster also provides a source of calcium in the area of the implant and stimulates revascularization and bone formation.
Conventional pharmaceutical grade Plaster of Paris or like calcium sulfate hemihydrate may be used for present purposes. Similarly, any available calcium phosphate ceramic particles may be employed. Preferably, however, these are composed of hydroxylapatite (HA), tricalcium phosphate (TCP--e.g. Augmen) or mixtures thereof. Hydroxylapatite particles are available, for example, as Calcitite 20-40 or Durapatite 18-40. Such particles are obtained by sintering or firing the mineral hydroxylapatite Ca.sub.10 (PO.sub.4).sub.6 (OH).sub.2 at about 1200.degree. C.